I have both LibreOffice and OpenOffice installed on a Windows 7 machine. The installer kept telling me to exit the LibreOffice 3.4 quick starter (which wasn't running) until I closed my OpenOffice quick starter. Then it kept telling me to close my LibreOffice 3.5 quick starter (and exit LibreOffice) even though neither was installed yet. I had to actually uninstall 3.4.3 before the install would work. Functionality appears normal once the install is complete, however.
*** This bug has been marked as a duplicate of bug 36677 ***